The present invention relates to a mass spectrometer.
A method for introducing ions generated in an atmospheric-pressure or low-vacuum chamber into a mass spectrometry part which requires a high vacuum of 10−1 Pa or less for mass spectrometry operation in a mass spectrometer is an important technique for implementing a high sensitivity.
In Analytical Chemistry, 2007, 79, 20, 7734-7739, Adam Keil, et al. a method for introducing ions supplied from an atmospheric-pressure ion source directly into the mass spectrometry part using a thin capillary provided between the atmospheric-pressure ion source and a high-vacuum chamber having the mass spectrometry part disposed therein is described. This configuration is the simplest configuration for connecting the atmospheric-pressure ion source and the mass spectrometry part in the high-vacuum chamber.
In U.S. Pat. No. 7,592,589 a differential pumping method used most typically in mass spectrometry is described. According to it, one or more of differential pumping chambers having medium pressures are disposed between an atmospheric-pressure ion source and a vacuum chamber having a mass spectrometry part disposed therein and respective chambers are evacuated by different vacuum pumps. As a result, it is possible to introduce ions generated at the atmospheric pressure remarkably efficiently as compared with one in Analytical Chemistry, 2007, 79, 20, 7734-7739, Adam Keil, et al.
In WO 2009/023361 a method of connecting an atmospheric-pressure ion source and a high-vacuum chamber having a mass spectrometry part disposed therein through a capillary, installing a pulse valve in between, and controlling opening/closing timewise is described. When the pulse valve is open, ions generated at the atmospheric pressure are introduced into the mass spectrometry part in the high-vacuum chamber. Then, the pulse valve is closed. After the pressure in the high-vacuum chamber is decreased, the mass spectrometry part is operated. As a result, it becomes possible to increase the amount of introduced ions by a large amount compared with one in Analytical Chemistry, 2007, 79, 20, 7734-7739, Adam Keil, et al. even in the case where a similar vacuum pump is used.
In U.S. Pat. No. 7,230,234 a method of installing a shutter-style pulse valve between an ion source disposed in a medium vacuum or a high vacuum of 5×10−2 Pa or less and a high-vacuum chamber having a time-of-flight type mass spectrometer disposed therein is described. According to this method, degradation of the time-of-flight type mass spectrometry part can be improved by controlling a flow of ions which flow into the high-vacuum chamber.
In U.S. Pat. No. 6,828,550 a shutter for introducing ions generated at the atmospheric pressure into an ion trap (described as ion reservoir) disposed in a medium-vacuum or high-vacuum chamber of 10−2 Pa or less in a pulsed manner is described. A shutter for controlling the ejection and injection in a pulsed manner when ions are accumulated in the ion trap disposed in the middle-vacuum or high-vacuum chamber of 10−2 Pa or less and introduced into a mass spectrometry part in the high-vacuum chamber is also described.